1. Field of the Invention
The present invention relates to a semi-automatic shift implementation control system/method for semi-automatic shifting of a lever-shifted, splitter-type mechanical transmission. More particularly, in a preferred embodiment of the present invention, a splitter or combined splitter-and-range-type compound transmission is provided with a splitter clutch at the output end of the transmission and with controls and actuators for manually performed dynamic forward main section shifting, by lever shifting, without requiring manual throttle manipulation to synchronize for engaging the target gear ratio, as is done for shifting a manual synchronized transmission. In a preferred embodiment, an intent-to-shift sensor is provided, allowing the transmission to be manually shifted without master clutch manipulation, if desired.
2. Description of the Prior Art
Compound mechanical transmissions of the splitter and the combined splitter-and-range type are widely used for heavy-duty vehicles and very well known in the prior art, as may be seen by reference to U.S. Pat. Nos. 4,735,109; 4,754,665; 4,944,197; 5,193,410 and 5,390,561, the disclosures of which are incorporated herein by reference.
Semi-automatic shift implementation systems for compound mechanical transmissions wherein, upon manual shifting into a highest grouping of gear ratios, automatic shifting within only that highest grouping is provided, are known in the prior art and are disclosed in U.S. Pat. Nos. 4,722,248 and 5,038,627, the disclosures of which are incorporated herein by reference. Semi-automatic shift implementation systems for mechanical transmissions wherein the vehicle operator is required to manually cause a torque interruption and/or achieve synchronous conditions are known in the prior art and are disclosed in U.S. Pat. No. 5,053,961, the disclosure of which is incorporated herein by reference.
At least partially automated systems wherein engine fuel control, such as engine dither, is utilized to cause non-torque-lock conditions for shifting into neutral without requiring master clutch manipulation and/or to synchronize for the target gear ratio are known in the prior art and are disclosed in U.S. Pat. Nos. 4,850,236; 5,105,357; 5,569,115; 5,523,477; 5,582,558 and allowed copending application 08/649,833, the disclosures of which are incorporated herein by reference.
U.S. Pat. No. 5,435,212, the disclosure of which is incorporated herein by reference, discloses a semi-automatic shift implementation system which, for each lever position, has automatic splitter shifting, which allows a "(2+1).times.(2).times.(2)" type compound 10-speed transmission to be driven with the ease of a 5-speed manual transmission.
Fully synchronized manual transmissions are well known and widely utilized for automobile, for light- and medium-duty trucks and, especially in Europe and Asia, for heavy-duty trucks. Examples of such transmissions may be seen by reference to U.S. Pat. Nos. 4,428,469; 4,989,706; 5,588,516; 5,390,561 and 5,267,636, the disclosures of which are incorporated herein by reference.
The above systems, as disclosed, were not totally satisfactory for certain applications, as the operator was possibly required to manipulate the splitter control and/or the throttle and/or master clutch for lever shifts, the systems may be more expensive and/or less reliable than desired and/or require excessive shift effort.
The systems for automatically synchronizing manual lever shifts as illustrated in aforementioned U.S. Pat. Nos. 5,569,115; 5,573,477; 5,582,558 and allowed copending application 08/649,833 may be difficult to utilize for drivers accustomed to driving manual synchronized transmissions, as manually disengaging the master clutch will hinder or prevent proper operation of the systems.